The evidence? Although everyone can benefit from dietary sources of essential fatty acids, supplementation is especially recommended for people with heart disease. A small study published in 2013 found that DHA may enhance memory and reaction time in healthy young adults. However, a more recent review suggested that there is not enough evidence of any effect from omega 3 supplementation in the general population.
[…] The verdict is out on brain health and aging. Scientists now know that memory loss and cognitive decline are not an inevitable part of growing older. In fact, the research proves quite the contrary. You can keep your mind sharp well into old age with a strategy that combines a healthy, active lifestyle with a brain-protecting diet and brain-boosting supplements. […]
The brain of animals features in French cuisine, in dishes such as cervelle de veau and tête de veau. A dish called maghaz is a popular Muslim cuisine in Pakistan, Bangladesh, parts of India, and diaspora countries. In Turkish cuisine brain can be fried, baked, or consumed as a salad. In Chinese cuisine, brain is a delicacy in Chongqing or Sichuan cuisine, and it is often cooked in spicy hot pot or barbecued. In the southern part of China, pig brain is used for "Tianma Zhunao Tang". In South India goat brain curry or fry is a delicacy.
The Blood Brain Barrier (BBB) is similar in structure to the intestinal barrier (6) and is usually highly selective, allowing certain required metabolic products such as short chain fatty acids and amino acids to pass into the brain from our wider circulation but protecting the brain from potentially damaging components. When the BBB is compromised, unwanted translocation may occur such as allowing a bacterial invasion, which can alter the function of immune cells that are responsible for regulating inflammation. Chronic inflammation is associated with many mental and physical health problems, so it is therefore suggested that poor gut health can have a direct correlation to poor mental wellbeing, as a result of a compromised intestinal barrier and the negative impact this has on our brain’s own structural barrier (BBB) and resulting inflammation.
Nuts and seeds are terrific sources of vitamin E, which, according to a 2014 study, can help prevent cognitive decline and Alzheimer’s disease as you age. Other vitamin E-rich foods include eggs and cooked veggies. And it’s not just your brain that benefits from nuts; your heart will be happier too. Almonds, walnuts, cashews, Brazil nuts, pistachios, and peanuts have been linked to a decreased risk of cardiovascular disease, according to a Harvard study. Try these other vitamin E-rich foods.
A constituent of the turmeric spice, curcumin was first discovered for its brain health benefits when epidemiological studies revealed those in regions with a high consumption of the curry spice turmeric had fewer reported cases of cognitive diseases. It is theorized that the unmatched anti-inflammatory power of curcumin, in combination with its unique antioxidant make-up, inhibits the formation of amyloid build up in the brain.
With just 16 predictions, I can’t simply bin the predictions and say yep, that looks good. Instead, we can treat each prediction as equivalent to a bet and see what my winnings (or losses) were; the standard such proper scoring rule is the logarithmic rule which pretty simple: you earn the logarithm of the probability if you were right, and the logarithm of the negation if you were wrong; he who racks up the fewest negative points wins. We feed in a list and get back a number:
According to Dr Vivette Glover, Director of the Foetal and Neonatal Stress and Research Centre, at any one time during pregnancy, one in every ten women will be depressed and around one in every thirty will be depressed both during pregnancy and the postnatal period (1). It is not yet understood exactly what causes the symptoms associated to depression during and after pregnancy. However, factors such as the large changes that the body undergoes due to the demands of the growing foetus, as well as breastfeeding and potential sleep deprivation, can all play a significant role in how the body deals with stress. It is during this period of time that our bodies require more nourishment from food than ever and it can also be at exactly this time when we perhaps struggle to prioritise nutrition due to lack of energy, loss of appetite or sickness. 

But before you dismiss the diet-brain connection as mere conjecture, keep in mind that study after study has found a relationship between what we put in our mouths and how well we can perform important thinking and memory tasks. While certain nutrients may specifically assist brain function, there is also the totality of our diets to consider. One recent U.K. study found that a diet high in saturated fat actually caused damage to neurons that control energy and appetite in mice. And several well-regarded studies have shown that meal timing is an important predictor of performance. For example, research shows that eating breakfast can improve the memory and acquisition skills of schoolchildren.

The experiment then is straightforward: cut up a fresh piece of gum, randomly select from it and an equivalent dry piece of gum, and do 5 rounds of dual n-back to test attention/energy & WM. (If it turns out to be placebo, I’ll immediately use the remaining active dose: no sense in wasting gum, and this will test whether nigh-daily use renders nicotine gum useless, similar to how caffeine may be useless if taken daily. If there’s 3 pieces of active gum left, then I wrap it very tightly in Saran wrap which is sticky and air-tight.) The dose will be 1mg or 1/4 a gum. I cut up a dozen pieces into 4 pieces for 48 doses and set them out to dry. Per the previous power analyses, 48 groups of DNB rounds likely will be enough for detecting small-medium effects (partly since we will be only looking at one metric - average % right per 5 rounds - with no need for multiple correction). Analysis will be one-tailed, since we’re looking for whether there is a clear performance improvement and hence a reason to keep using nicotine gum (rather than whether nicotine gum might be harmful).
One reason I like modafinil is that it enhances dopamine release, but it binds to your dopamine receptors differently than addictive substances like cocaine and amphetamines do, which may be part of the reason modafinil shares many of the benefits of other stimulants but doesn’t cause addiction or withdrawal symptoms. [3] [4] It does increase focus, problem-solving abilities, and wakefulness, but it is not in the same class of drugs as Adderall, and it is not a classical stimulant. Modafinil is off of patent, so you can get it generically, or order it from India. It’s a prescription drug, so you need to talk to a physician.
A study published in the Journal of Environmental Healths Perspective stated that "researchers, physicians, and others poked around in the dark crevices of the gene, (are) trying to untangle the clues that suggested gene function could be altered by more than just changes in sequence." This ties in perfectly with what Dr. Lisa mentions about how our lifestyles play a crucial role in how/if we manifest a certain cognitive disfunction. Which brings us to our next question: What kind of "brain diet" can help support this lifestyle?

Bacopa is a supplement herb often used for memory or stress adaptation. Its chronic effects reportedly take many weeks to manifest, with no important acute effects. Out of curiosity, I bought 2 bottles of Bacognize Bacopa pills and ran a non-randomized non-blinded ABABA quasi-self-experiment from June 2014 to September 2015, measuring effects on my memory performance, sleep, and daily self-ratings of mood/productivity. Because of the very slow onset, small effective sample size, definite temporal trends probably unrelated to Bacopa, and noise in the variables, the results were as expected, ambiguous, and do not strongly support any correlation between Bacopa and memory/sleep/self-rating (+/-/- respectively).
Jump up ^ EFSA Panel on Dietetic Products, Nutrition and Allergies; European Food Safety Authority (EFSA), Parma, Italy (2011). "Scientific Opinion on the substantiation of health claims related to L-theanine from Camellia sinensis (L.) Kuntze (tea) and improvement of cognitive function (ID 1104, 1222, 1600, 1601, 1707, 1935, 2004, 2005), alleviation of psychological stress (ID 1598, 1601), maintenance of normal sleep (ID 1222, 1737, 2004) and reduction of menstrual discomfort (ID 1599) pursuant to Article 13(1) of Regulation (EC) No 1924/2006". EFSA Journal. 9 (6): 2238. doi:10.2903/j.efsa.2011.2238.
Looking at the prices, the overwhelming expense is for modafinil. It’s a powerful stimulant - possibly the single most effective ingredient in the list - but dang expensive. Worse, there’s anecdotal evidence that one can develop tolerance to modafinil, so we might be wasting a great deal of money on it. (And for me, modafinil isn’t even very useful in the daytime: I can’t even notice it.) If we drop it, the cost drops by a full $800 from $1761 to $961 (almost halving) and to $0.96 per day. A remarkable difference, and if one were genetically insensitive to modafinil, one would definitely want to remove it.
Huperzine A: This compound is found in a firmoss plant called Huperzia serrata.  Studies conducted on Huperzine A so far have not used the best methodology, so scientists are still not sure how beneficial this compound is for preventing or treating Alzheimer’s disease.  But one review of studies on Huperzine A concluded that the compound “appears to have beneficial effects on improvement of cognitive function, daily living activity, and global clinical assessment in participants with Alzheimer’s disease.”
Another traditional Chinese brain booster is Danggui-Shaoyao-San (DSS). It has been suggested that DSS has potent beneficial angiogenesis and neurogenesis effects that may make it a potential treatment for ischemic stroke therapy. DSS is also known to beneficially impact free radical-mediated neurological diseases, exhibit anti-inflammatory and antioxidant activities and reduce cell death in the hippocampus, thereby promoting greater emotional, memory-related and autonomic nervous system function. Currently, there is limited research on proper dosage, but you can learn more about DSS in this fantastic summary article on it’s interplay with Alzheimer’s.
The use of cognition-enhancing drugs by healthy individuals in the absence of a medical indication spans numerous controversial issues, including the ethics and fairness of their use, concerns over adverse effects, and the diversion of prescription drugs for nonmedical uses, among others.[1][2] Nonetheless, the international sales of cognition-enhancing supplements exceeded US$1 billion in 2015 when global demand for these compounds grew.[3]